Cluster analysis is the task of grouping objects based on data that describes the objects and their relationships. The goal of cluster analysis is to group a set of objects in such a way that objects in a same group (i.e., a cluster) are more similar to each other than to objects in other groups. The greater the similarity (i.e., homogeneity) within a group and the greater the difference between groups, the better or more distinct the clustering. In cluster analysis, the unclassified results from a formal clustering algorithm are typically presented to a domain expert to interpret and validate the significance of the clusters.